Abstract: The purpose of the study is to establish effect function models of N, P, K fertilizer balanced application on the flue-cured tobacco crops under the tobacco-rice rotation system area of Southern and Central Hunan, and to determine the reasonable fertilization rate of tobacco, by using the design of “3414” experiment suggested by FAO with some modification, the field plot experiment was carried out to investigate the effect of different applying rate of N, P and K fertilizer on the flue-cured tobacco crops under the tobacco-rice rotation system area of Southern and Central Hunan, and to estimate the optimum fertilization rate for the scientific and reasonable fertilization recommendation. The results showed that, the native contribution of tobacco soil for production of flue-cured tobacco was much smaller, and the economic product yield of flue-cured tobacco of no fertilizer plot only accounts for 36.4%-39.4% that of the balanced NPK fertilization plot (treatment 6). In this study, the fertilizer which had the largest increasing production for economic yield was nitrogen, which had the increased production was 719.6 kg/hm2, 1109.7 kg/hm2 and 441.0 kg/hm2 in Nongda, Yongzhou and Changning site, respectively. The data of “3414” experiment at three experiment sites could not be fitted in with the binary quadratic fertilizer response function successfully, one-place quadratic fertilizer response function could be used at Nongda experiment site, and its optimum fertilization rate in this experiment condition were N 159.8 kg/hm2, P2O5 86.1 kg/hm2 and K2O 152.2 kg/hm2 respectively. Terrnary quadratic fertilizer response function could be used at Yongzhou experiment site, and its optimum fertilization rate in this experiment condition was N 175.2 kg/hm2, P2O5 52.1 kg/hm2 and K2O 278.3 kg/hm2 respectively. One-place quadratic fertilizer response function could be recommended at Changning experiment site, and its optimum fertilization rate in this experiment condition was N 178.7 kg/hm2, P2O5 107.8 kg/hm2 and K2O 279.2 kg/hm2, respectively. By summarizing the data of the above “3414” experiment, the optimum fertilization parametes of tobacco plants fertilization decision could be obtained and the optimum fertilization rate of N, P and K were N 172.2 kg/hm2, P2O5 93.3 kg/hm2, K2O 300.0 kg/hm2 in double cropping rice area of the South Central of Hunan, respectively.